Field of the Invention
The present invention relates to a zoom lens and an image pickup apparatus.
Description of the Related Art
Heretofore, an image pickup optical system used with an image pickup apparatus (camera) is required to be a zoom lens having a wide angle of view so as to encompass a wider range in one image, and having high optical performance over the entire zoom range and all object distances. The image pickup optical system is also required to have an image stabilization function for suppressing degradation of an image due to image blur caused by an oscillation, for example, hand shake at the time of photography, so as to obtain a high-definition image, for example.
In the related art, as a zoom lens that easily achieves the wide angle of view, there is known a negative lead type zoom lens, in which a lens unit having a negative refractive power is located closest to an object side (Japanese Patent Application Laid-Open No. 2008-046208). There is also known a negative lead type zoom lens having a wide angle of view and an image stabilization function, with which a lens forming a part of an optical system is moved in a direction having a component in a direction perpendicular to an optical axis to correct the image blur (US Patent Application Publication No. 2012/0069441 and U.S. Pat. No. 5,835,272).
In each of Japanese Patent Application Laid-Open No. 2008-046208, US Patent Application Publication No. 2012/0069441, and U.S. Pat. No. 5,835,272, there is disclosed a four-unit zoom lens consisting of, in order from an object side to an image side, first to fourth lens units having negative, positive, negative, and positive refractive indices, in which an interval between each pair of lens units is changed to perform zooming. Of the related art, in US Patent Application Publication No. 2012/0069441, the entire third lens unit is configured to move in a direction substantially perpendicular to the optical axis to perform image stabilization. In US Patent Application Publication No. 2012/0069441, a lens unit forming a part of the third lens unit is configured to correct the image blur, and a lens unit forming a part of the second lens unit is configured to perform focusing.
In a negative lead type zoom lens, when an image pickup angle of view is about 100°, it becomes very difficult to correct various aberrations. For example, large decentering aberration is generated during the image stabilization, and it becomes very difficult to obtain the high optical performance.